This photography fundamentals session looks at the theory behind time-lapse photography: how it works and what you can use it to achieve. For a collection of time-lapse videos from across the world, housed in one place, check out Primelapse. If you feel inspired and want to have a go at trying it yourself, we've a tutorial on that, too!

Speeding up time

Anyone who has ever watched a nature documentary will be familiar with time-lapse photography, even if they couldn't identify the technique itself as time-lapse. When you watch an African riverbed flood and desiccate and flood again over the course of a year, but the footage has been condensed into a running time of thirty seconds, that's time-lapse. Seeing a plant grow, flower, and die within the space of ten seconds would have been achieved using time-lapse photography, too.

The Oxford English Dictionary's definition of time-lapse photography is:

the photographic technique of taking a sequence of frames at set intervals to record changes that take place slowly over time. When the frames are shown at normal speed the action seems much faster.

The difference is in the frame-rates

How about a photographically or cinematographically-oriented explanation? Video is made by shooting a series of photographs (or frames) in succession and then stringing them together so that they can be watched in sequence. Films shown in the cinema are usually filmed at 24 frames-per-second; depending on where you are in the world, television programmes will have a frame-rate of 24 or 25 frames-per-second. When they're played back at 24 or 25 frames-per-second it gives the impression of things happening in 'real time'.

The time-lapse sequences in the nature documentary, however, will have a much slower frame-rate with a significant period of time elapsing between each shot. They might have been 60 frames-per-minute, or six frames per minute, or 24 frames per day. When these frames are strung together and shown as a video replayed at 24 or 25 frames-per-second, it makes whatever was recorded appear to take place faster than it really did. It's an excellent technique for documenting change and a great first step into film-making.

Documenting change

For anyone interested in having a go at time-lapse photography, it will require identifying a subject that is going to change over time, taking a series of photographs of this subject as it morphs, and then piecing together these photographs to create a video. The result will be a video showing the change happening faster than it really did. You don't have to worry about recording sound, about focus-pulling or panning, or about directing your subjects. All you really have to remember is that the faster the change takes place, the shorter the interval between each shot will need to be. This is why a pregnant woman's swelling belly can be documented with one photo a day but a melting ice cube will need several shots every minute over the course of, say, 30 minutes.

Time-elapsed sequences can be as involved or as simple as you want. They can be shot over a matter of minutes, for example drifting and shifting clouds; the span of months, such as the construction of a building; the course of years, or anything in between. They can be taken on the move, for example in a car or on a bus. And they can involve shifting vantage points and changes in focus as you grow more sophisticated. The key is to have a subject that is changing.

If you were to reverse the time-lapse process and shoot hundreds or thousands of frames-per-second and replay them at 'normal' speed, or 24, 25, or 30 frames-per-second, you would create the opposite effect: slow-motion photography!

TL;DR

Time-lapse photography is a technique that is often used to document change
It works by shooting a series of images over a period of time but playing them back at 'normal' cinematic or televisual speed; this gives the impression that things happened faster than they did in reality
Time-lapse photography projects can take place over minutes, days, months, or years
The faster that something changes, the shorter the interval between frames is needed to document it

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